This study examined the psychometric properties and feasibility of the Illness Management and Recovery (IMR) Fidelity scale. Despite widespread use of the scale, the psychometric properties have received limited attention. Trained fidelity assessors conducted assessments four times over 18 months at 11 sites implementing IMR. The IMR Fidelity scale showed excellent interrater reliability (.99), interrater item agreement (94%), internal consistency (.91-.95 at three time points), and sensitivity to change. Frequency distributions generally showed that item ratings included the entire range. The IMR Fidelity scale has excellent psychometric properties and should be used to evaluate and guide the implementation of IMR.Trial registration: ClinicalTrials.gov Identifier: NCT03271242.
Keywords: IMR Fidelity scale; Illness Management and Recovery; Measurement; Psychometric properties.